Fluorescent orange latex with enhanced brightness and toners made therefrom

ABSTRACT

Fluorescent orange latexes are provided which comprise water and fluorescent agent-incorporated resin particles, the particles comprising a resin, Solvent Red 49 as a red fluorescent agent, and Solvent Yellow 98 as a yellow fluorescent agent, wherein the fluorescent orange latex has a weight ratio of the Solvent Yellow 98 to the Solvent Red 49 in a range of from 20:1 to 0.5:1. Fluorescent orange toners and methods of making and using the fluorescent orange toners are also provided.

BACKGROUND

Conventional xerographic printing systems for toner applications consistof four stations comprising cyan, magenta, yellow, and black (CMYK)toner stations. These and other xerographic printing systems can be madeto print specialty colors, including fluorescent toners. A variety offluorescent toners have been developed, but improved fluorescent tonersare desirable.

SUMMARY

The present disclosure provides fluorescent orange latexes andcompositions formed from the fluorescent orange latexes, such as tonersand inkjet printing compositions. Related methods are also provided.

In one aspect, fluorescent orange latexes are provided. In embodiments,a fluorescent orange latex comprises water and fluorescentagent-incorporated resin particles, the particles comprising a resin,Solvent Red 49 as a red fluorescent agent, and Solvent Yellow 98 as ayellow fluorescent agent, wherein the fluorescent orange latex has aweight ratio of the Solvent Yellow 98 to the Solvent Red 49 in a rangeof from 20:1 to 0.5:1.

In another aspect, fluorescent orange toners are provided. Inembodiments, a fluorescent orange toner comprises fluorescentagent-incorporated resin particles, the particles comprising a resin,Solvent Red 49 as a red fluorescent agent, and Solvent Yellow 98 as ayellow fluorescent agent, wherein the fluorescent orange latex has aweight ratio of the Solvent Yellow 98 to the Solvent Red 49 in a rangeof from 20:1 to 0.5:1.

In another aspect, methods of making fluorescent orange toners areprovided. In embodiments, such a method comprises forming one or morefluorescent latexes which comprise Solvent Red 49 as a red fluorescentagent, Solvent Yellow 98 as a yellow fluorescent agent, a first type ofamorphous resin, and a second type of amorphous resin, wherein theSolvent Yellow 98 and the Solvent Red 49 and are present in a weightratio in a range of from 20:1 to 0.5:1; forming a mixture comprising theone or more fluorescent latexes; one or more emulsions which comprise acrystalline resin, the first type of amorphous resin, the second type ofamorphous resin; and optionally, a wax dispersion; aggregating themixture to form particles of a predetermined size; forming a shell overthe particles of the predetermined size to form core-shell particles;and coalescing the core-shell particles to form a fluorescent orangetoner.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative embodiments of the disclosure will hereafter be describedwith reference to the accompanying drawings.

FIG. 1 shows color channel data for fluorescent orange latexes accordingto an illustrative embodiment. The toner mass area (TMA) was 0.5 mg/cm².

FIG. 2 shows reflectance spectra of fluorescent orange toners accordingto an illustrative embodiment. The TMA was 0.5 mg/cm².

DETAILED DESCRIPTION

The present disclosure provides fluorescent orange latexes andcompositions formed from the fluorescent orange latexes, such as tonersand inkjet printing compositions. Related methods are also provided.

The present fluorescent orange latexes comprise fluorescentagent-incorporated resin particles which are resin particles havingincorporated therein a red fluorescent agent and a yellow fluorescentagent. Although some fluorescent latexes for toners have been developed,the brightness of such latexes and toners has been limited. The presentdisclosure is based, at least in part, on the use of a specific pair offluorescent agents, Solvent Red 49 as the red fluorescent agent andSolvent Yellow 98 as the yellow fluorescent agent. It has been foundthat this pair is particularly advantageous as the pair is capable ofundergoing Förster resonance energy transfer (FRET). As such, the pairmay be referred to as a FRET pair. In order to form a FRET pair, theemission spectrum of the yellow fluorescent agent must adequatelyoverlap with the absorption spectrum of the red fluorescent agent. Uponillumination with light to excite the yellow fluorescent agent, theexcited yellow fluorescent agent transfers energy to the red fluorescentagent via nonradiative energy transfer to induce fluorescence emissionfrom the red fluorescent agent. The greater the degree of overlapbetween the normalized emission spectrum of the yellow fluorescent agentand the normalized absorption spectrum of the red fluorescent agent, thegreater the FRET efficiency and the greater the overall fluorescenceemission from the fluorescent latex and compositions formed from thefluorescent latex. In the case of Solvent Yellow 98 and Solvent Red 49,the degree of overlap is very large, about >90%.

As demonstrated in the Example, below, an additional advantage of theSolvent Yellow 98 and Solvent Red 49 pair relates to the orange colorspace defined by a color channel a* range of from 40 to 85 and a colorchannel b* range of from 40 to 85. (Color channels a*, b* are describedfurther below). This FRET pair covers a very large area in this orangecolor space, thereby providing a much greater gamut of orange color ascompared to Solvent Red 49 combined with other yellow fluorescent agentssuch as Solvent Yellow 160:1. In addition, a much greater amount ofSolvent Yellow 98 may be added (as compared to Solvent Yellow 160:1)while still providing an orange color. This further enhances thereflectance (brightness) of the fluorescent orange latex andcompositions thereof. This is also demonstrated in the Example, below.

In embodiments, the present fluorescent orange latexes further comprisea fluorescent brightener. The fluorescent brightener may also beselected such that it forms another FRET pair with the yellowfluorescent agent, the red fluorescent agent, or both. Moreover, thefluorescent brightener may be selected to provide a desired degree ofoverlap with the absorption spectrum of its partner, e.g., greater than5%, greater than 15%, greater than 20%, greater than 30%, or in a rangeof from 30% to 100%.

In embodiments, the fluorescent brightener has an absorption spectrumspanning a range of from 300 nm to 400 nm and an emission spectrumspanning a range of from 380 nm to 650 nm. This includes the fluorescentbrightener having an absorption spectrum spanning a range of from 300 nmto 380 nm. This includes the fluorescent brightener having an emissionspectrum spanning a range of from 400 nm to 550 nm. It is also desirablethat the fluorescent brightener absorb no light in a range of from 380nm to 700 nm. The phrase “no light” encompasses zero but also a smallamount of absorption, provided the fluorescent brightener appearscolorless to the human eye.

FRET efficiency is also related to the separation distance (d) betweendonor fluorescent agent and acceptor fluorescent agent molecules(efficiency ∝d⁻⁶). Thus, to actually achieve FRET in the presentfluorescent orange latexes, the red and yellow fluorescent agents and ifpresent, the fluorescent brightener, are sufficiently close together(i.e., present at sufficiently high concentration, although not so highas to result in fluorescence quenching) and homogeneously distributed inthe resin particles. The method of forming the fluorescent orangelatexes as further described below achieves such an appropriateconcentration and homogeneous distribution. Confirmation of FRET may becarried out as further described below.

Illustrative fluorescent brighteners include the following: FluorescentBrightener 184, Optical Brightener 1 (Fluorescent Brightening Agent393), Optical Brightener 2, Optical Brightener 3, Optical Brightener C,Optical Brightener OB, Optical Brightener R, Optical Brightener HostaluxKSN, Optical Brightener Hostalux KCB, Optical Brightener Telalux KSB,Fluorescent Brightener 127, CBS-127, Optical Brightener PF, OpticalBrightener UVT1, Optical Brightener ST, Optical Brightener OEF, OpticalBrightener RT, Tinopal CBS-X, DMS/AMS, CBS-155, 378, 367, 368, 185, 199,199:1, 199:2, Optical Brightener ER-IV, Optical Brightener ER-V, OpticalBrightener 4BK, Optical Brightener ER-I/ER-I L, Optical BrightenerER-II/ER-II L, Optical Brightener EBF/EBF-L, PF/DT, BA, CXT, R4, MST-L,BAC, SWN/AW-L, WGS, NFW, PC, BBU/BBU-L, VBL/VBL-L. In embodiments, thefluorescent brightener is Fluorescent Brightener 184. Combinations ofdifferent types of fluorescent brighteners may be used.

The relative amount of the yellow and red fluorescent agents is selectedto achieve a color channel a* of from 40 to 85 and a color channel b* offrom 40 to 85. This relative amount corresponds to a weight ratio ofyellow:red in a range of from 20:1 to 0.3:1. This includes a weightratio in a range of from 15:1 to 0.5:1, from 10:1 to 1:1, from 12:1 to1:1, from 11:1 to 2:1, and from 10:1 to 3:1. The relative amount of thefluorescent brightener, if present, as compared to the total amount ofthe red and yellow fluorescent agents may vary. In embodiments, theweight ratio of (fluorescent brightener):(red and yellow fluorescentagents) is in a range of from 1:200 to 1:0.01, from 1:50 to 1:0.05, orfrom 1:10 to 1:0.5. The total amount of the fluorescent agents (red,yellow, and brightener, if present) in the fluorescent orange latex maybe from 0.1 weight % to 10 weight % by weight of the fluorescent orangelatex. This includes a total amount of from 0.1 weight % to 8 weight %,from 0.2 weight % to 6 weight %, from 0.5 weight % to 5 weight %, andfrom 1 weight % to 2 weight %. These ranges are useful to achieve anappropriate concentration to ensure FRET while also preventingfluorescence quenching.

Resins

The resin particles of the present fluorescent orange latexes provide apolymeric matrix to contain the red and yellow fluorescent agents andthe fluorescent brightener, if present. The resin particles may comprisemore than one different type of resin. The resin may be an amorphousresin, a crystalline resin, a mixture of amorphous resins, or a mixtureof crystalline and amorphous resins. The resin may be a polyester resin,including an amorphous polyester resin, a crystalline polyester resin, amixture of amorphous polyester resins, or a mixture of crystalline andamorphous polyester resins. It is noted that this section also describesresins which may be included in compositions formed from the presentfluorescent orange latexes, e.g., toners.

Crystalline Resin

The resin may be a crystalline polyester resin formed by reacting a diolwith a diacid in the presence of an optional catalyst. For forming acrystalline polyester, suitable organic diols include aliphatic diolswith from about 2 to about 36 carbon atoms, such as 1,2-ethanediol,1,3-propanediol, 1,4-butanediol, 1,5-pentanediol,2,2-dimethylpropane-1,3-diol, 1,6-hexanediol, 1,7-heptanediol,1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol,combinations thereof, and the like including their structural isomers.The aliphatic diol may be, for example, selected in an amount of fromabout 40 to about 60 mole percent of the resin, from about 42 to about55 mole percent of the resin, or from about 45 to about 53 mole percentof the resin, and a second diol may be selected in an amount of fromabout 0 to about 10 mole percent of the resin or from about 1 to about 4mole percent of the resin.

Examples of organic diacids or diesters including vinyl diacids or vinyldiesters selected for the preparation of crystalline resins includeoxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid,azelaic acid, sebacic acid, fumaric acid, dimethyl fumarate, dimethylitaconate, cis, 1,4-diacetoxy-2-butene, diethyl fumarate, diethylmaleate, phthalic acid, isophthalic acid, terephthalic acid,naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid,cyclohexane dicarboxylic acid, malonic acid and mesaconic acid, adiester or anhydride thereof. The organic diacid may be selected in anamount of, for example, from about 40 to about 60 mole percent of theresin, from about 42 to about 52 mole percent of the resin, or fromabout 45 to about 50 mole percent of the resin, and a second diacid canbe selected in an amount of from about 0 to about 10 mole percent of theresin.

Polycondensation catalysts which may be utilized in forming crystalline(as well as amorphous) polyesters include tetraalkyl titanates,dialkyltin oxides such as dibutyltin oxide, tetraalkyltins such asdibutyltin dilaurate, and dialkyltin oxide hydroxides such as butyltinoxide hydroxide, aluminum alkoxides, alkyl zinc, dialkyl zinc, zincoxide, stannous oxide, or combinations thereof. Such catalysts may beutilized in amounts of, for example, from about 0.01 mole percent toabout 5 mole percent based on the starting diacid or diester used togenerate the polyester resin.

Examples of crystalline resins include polyesters, polyamides,polyimides, polyolefins, polyethylene, polybutylene, polyisobutyrate,ethylene-propylene copolymers, ethylene-vinyl acetate copolymers,polypropylene, mixtures thereof, and the like. Specific crystallineresins may be polyester based, such as poly(ethylene-adipate),poly(propylene-adipate), poly(butylene-adipate),poly(pentylene-adipate), poly(hexylene-adipate), poly(octylene-adipate),poly(ethylene-succinate), poly(propylene-succinate),poly(butylene-succinate), poly(pentylene-succinate),poly(hexylene-succinate), poly(octylene-succinate),poly(ethylene-sebacate), poly(propylene-sebacate),poly(butylene-sebacate), poly(pentylene-sebacate),poly(hexylene-sebacate), poly(octylene-sebacate),poly(decylene-sebacate), poly(decylene-decanoate),poly(ethylene-decanoate), poly(ethylene dodecanoate),poly(nonylene-sebacate), poly(nonylene-decanoate),copoly(ethylene-fumarate)-copoly(ethylene-sebacate),copoly(ethylene-fumarate)-copoly(ethylene-decanoate),copoly(ethylene-fumarate)-copoly(ethylene-dodecanoate),copoly(2,2-dimethylpropane-1,3-diol-decanoate)-copoly(nonylene-decanoate),poly(octylene-adipate), and mixtures thereof. Examples of polyamidesinclude poly(ethylene-adipamide), poly(propylene-adipamide),poly(butylenes-adipamide), poly(pentylene-adipamide),poly(hexylene-adipamide), poly(octylene-adipamide),poly(ethylene-succinimide), poly(propylene-sebecamide), and mixturesthereof. Examples of polyimides include poly(ethylene-adipimide),poly(propylene-adipimide), poly(butylene-adipimide),poly(pentylene-adipimide), poly(hexylene-adipimide),poly(octylene-adipimide), poly(ethylene-succinimide),poly(propylene-succinimide), poly(butylene-succinimide), and mixturesthereof.

In embodiments, the crystalline polyester resin has the followingformula (I)

wherein each of a and b may range from 1 to 12, from 2 to 12, or from 4to 12 and further wherein p may range from 10 to 100, from 20 to 80, orfrom 30 to 60. In embodiments, the crystalline polyester resin ispoly(1,6-hexylene-1,12-dodecanoate), which may be generated by thereaction of dodecanedioc acid and 1,6-hexanediol.

As noted above, the disclosed crystalline polyester resins may beprepared by a polycondensation process by reacting suitable organicdiols and suitable organic diacids in the presence of polycondensationcatalysts. A stoichiometric equimolar ratio of organic diol and organicdiacid may be utilized, however, in some instances where the boilingpoint of the organic diol is from about 180° C. to about 230° C., anexcess amount of diol, such as ethylene glycol or propylene glycol, offrom about 0.2 to 1 mole equivalent, can be utilized and removed duringthe polycondensation process by distillation. The amount of catalystutilized may vary, and can be selected in amounts, such as for example,from about 0.01 to about 1 or from about 0.1 to about 0.75 mole percentof the crystalline polyester resin.

The crystalline resin can possess various melting points of, forexample, from about 30° C. to about 120° C., from about 50° C. to about90° C., or from about 60° C. to about 80° C. The crystalline resin mayhave a number average molecular weight (M_(n)), as measured by gelpermeation chromatography (GPC) of, for example, from about 1,000 toabout 50,000, from about 2,000 to about 25,000, or from about 5,000 toabout 20,000, and a weight average molecular weight (M_(w)) of, forexample, from about 2,000 to about 100,000, from about 3,000 to about80,000, or from about 10,000 to about 30,000, as determined by GPC. Themolecular weight distribution (M_(w)/M_(n)) of the crystalline resin maybe, for example, from about 2 to about 6, from about 3 to about 5, orfrom about 2 to about 4.

Amorphous Resin

The resin may be an amorphous polyester resin formed by reacting a diolwith a diacid in the presence of an optional catalyst. Examples ofdiacids or diesters including vinyl diacids or vinyl diesters utilizedfor the preparation of amorphous polyesters include dicarboxylic acidsor diesters such as terephthalic acid, phthalic acid, isophthalic acid,fumaric acid, trimellitic acid, dimethyl fumarate, dimethyl itaconate,cis, 1,4-diacetoxy-2-butene, diethyl fumarate, diethyl maleate, maleicacid, succinic acid, itaconic acid, succinic acid, succinic anhydride,dodecylsuccinic acid, dodecylsuccinic anhydride, glutaric acid, glutaricanhydride, adipic acid, pimelic acid, suberic acid, azelaic acid,dodecanediacid, dimethyl terephthalate, diethyl terephthalate,dimethylisophthalate, diethylisophthalate, dimethylphthalate, phthalicanhydride, diethylphthalate, dimethylsuccinate, dimethylfumarate,dimethylmaleate, dimethylglutarate, dimethyladipate, dimethyldodecylsuccinate, and combinations thereof. The organic diacids ordiesters may be present, for example, in an amount from about 40 toabout 60 mole percent of the resin, from about 42 to about 52 molepercent of the resin, or from about 45 to about 50 mole percent of theresin.

Examples of diols which may be utilized in generating an amorphouspolyester include 1,2-propanediol, 1,3-propanediol, 1,2-butanediol,1,3-butanediol, 1,4-butanediol, pentanediol, hexanediol,2,2-dimethylpropanediol, 2,2,3-trimethylhexanediol, heptanediol,dodecanediol, bis(hydroxyethyl)-bisphenol A,bis(2-hydroxypropyl)-bisphenol A, 1,4-cyclohexanedimethanol,1,3-cyclohexanedimethanol, xylenedimethanol, cyclohexanediol, diethyleneglycol, bis(2-hydroxyethyl) oxide, dipropylene glycol, dibutylene, andcombinations thereof. The amount of organic diols selected may vary, forexample, the organic diols may be present in an amount from about 40 toabout 60 mole percent of the resin, from about 42 to about 55 molepercent of the resin, or from about 45 to about 53 mole percent of theresin.

Examples of suitable amorphous resins include polyesters, polyamides,polyimides, polyolefins, polyethylene, polybutylene, polyisobutyrate,ethylene-propylene copolymers, ethylene-vinyl acetate copolymers,polypropylene, and the like, and mixtures thereof.

An unsaturated amorphous polyester resin may be utilized as a resin.Examples of such resins include those disclosed in U.S. Pat. No.6,063,827, the disclosure of which is hereby incorporated by referencein its entirety. Exemplary unsaturated amorphous polyester resinsinclude, but are not limited to, poly(propoxylated bisphenolco-fumarate), poly(ethoxylated bisphenol co-fumarate),poly(butyloxylated bisphenol co-fumarate), poly(co-propoxylatedbisphenol co-ethoxylated bisphenol co-fumarate), poly(1,2-propylenefumarate), poly(propoxylated bisphenol co-maleate), poly(ethoxylatedbisphenol co-maleate), poly(butyloxylated bisphenol co-maleate),poly(co-propoxylated bisphenol co-ethoxylated bisphenol co-maleate),poly(1,2-propylene maleate), poly(propoxylated bisphenol co-itaconate),poly(ethoxylated bisphenol co-itaconate), poly(butyloxylated bisphenolco-itaconate), poly(co-propoxylated bisphenol co-ethoxylated bisphenolco-itaconate), poly(1,2-propylene itaconate), and combinations thereof.

A suitable polyester resin may be an amorphous polyester such as apoly(propoxylated bisphenol A co-fumarate) resin. Examples of suchresins and processes for their production include those disclosed inU.S. Pat. No. 6,063,827, the disclosure of which is hereby incorporatedby reference in its entirety.

Suitable polyester resins include amorphous acidic polyester resins. Anamorphous acid polyester resin may be based on any combination ofpropoxylated bisphenol A, ethoxylated bisphenol A, terephthalic acid,fumaric acid, and dodecenyl succinic anhydride, such aspoly(propoxylatedbisphenol-co-terephthlate-fumarate-dodecenylsuccinate). Anotheramorphous acid polyester resin which may be used ispoly(propoxylated-ethoxylatedbisphenol-co-terephthalate-dodecenylsuccinate-trimellitic anhydride).

An example of a linear propoxylated bisphenol A fumarate resin which maybe utilized as a resin is available under the trade name SPAMII fromResana S/A Industrias Quimicas, Sao Paulo Brazil. Other propoxylatedbisphenol A fumarate resins that may be utilized and are commerciallyavailable include GTUF and FPESL-2 from Kao Corporation, Japan, andEM181635 from Reichhold, Research Triangle Park, N.C., and the like.

The amorphous resin or combination of amorphous resins may have a glasstransition temperature of from about 30° C. to about 80° C., from about35° C. to about 70° C., or from about 40° C. to about 65° C. The glasstransition temperature may be measured using differential scanningcalorimetry (DSC). The amorphous resin may have a M_(n), as measured byGPC of, for example, from about 1,000 to about 50,000, from about 2,000to about 25,000, or from about 1,000 to about 10,000, and a M_(w) of,for example, from about 2,000 to about 100,000, from about 5,000 toabout 90,000, from about 10,000 to about 90,000, from about 10,000 toabout 30,000, or from about 70,000 to about 100,000, as determined byGPC.

The resin(s) in the present toners may possess acid groups which may bepresent at the terminal of the resin. Acid groups which may be presentinclude carboxylic acid groups, and the like. The number of carboxylicacid groups may be controlled by adjusting the materials utilized toform the resin and reaction conditions. In embodiments, the resin is apolyester resin having an acid number from about 2 mg KOH/g of resin toabout 200 mg KOH/g of resin, from about 5 mg KOH/g of resin to about 50mg KOH/g of resin, or from about 5 mg KOH/g of resin to about 15 mgKOH/g of resin. The acid containing resin may be dissolved intetrahydrofuran solution. The acid number may be detected by titrationwith KOH/methanol solution containing phenolphthalein as the indicator.The acid number may then be calculated based on the equivalent amount ofKOH/methanol required to neutralize all the acid groups on the resinidentified as the end point of the titration.

The present fluorescent orange latex may comprise a single type ofresin, e.g., a single type of amorphous polyester resin, or multipletypes of resins, e.g., two different types of amorphous polyesterresins. In such embodiments, one of the amorphous polyester resins hasan M_(n) or M_(w) that is greater than the other. In embodiments inwhich two different types of amorphous polyester resins are used, theweight ratio of the two types may be from 2:3 to 3:2. This includes aweight ratio of 1:1. Alternatively, two separate fluorescent orangelatexes may be used, each comprising a different type of amorphouspolyester resin. However, together, the fluorescent orange latex(es)provide the two different types of amorphous polyester resins withinthis range of weight ratios. These weight ratios are useful for ensuringa homogeneous distribution of the fluorescent agents once incorporatedinto the resin particles. This also prevents fluorescence quenchingwhile facilitating FRET.

The total amount of the resins may be present in the fluorescent orangelatex in an amount of, for example, from 1 weight % to 60 weight % byweight of the fluorescent latex. This includes total amounts of resin ina range of from 5 weight % to 50 weight % and from 10 weight % to 40weight %.

As noted above, the form of the fluorescent agent-incorporated resins isthat of particles. The particles may have an average size in a range offrom 20 nm to 1000 nm, as measured by dynamic light scattering.

Other Components

The present fluorescent orange latexes generally further comprise one ormore solvents, although they may also be utilized in a dried form. Wateris typically used as a solvent, but organic solvent(s) may be included.Other components may be included, e.g., one or more types of defoamers,one or more types of surfactants, one or more types of biocides.Surfactants include sodium dodecyl sulfate, Calfax/Dowfax, sodiumdioctyl sulfosuccinate, sodium dodecylbenzene sulfonate, etc. Biocidesinclude Proxel GXL, Kathon biocides, Bioban preservatives, Rocima 586Microblade, Ucarcide Antimicrobials, Dowicide Antimicrobials, etc.

Fluorescent Orange Latex Preparation

The fluorescent agent-incorporated resin particles and the fluorescentorange latexes comprising the particles may be prepared as follows. Amixture may be formed by combining the desired fluorescent agent, thedesired resin, and a solvent. The solvent may be a solvent systemcomprising one or more organic solvents (acetone, tetrahydrofuran, ethylacetate, methyl ethyl ketone, methylene chloride, methanol, ethanol,n-propyl alcohol, isopropyl alcohol, butanol, etc.) as well as water.Other additives may be included in the mixture, e.g., one or more typesof surfactants (see “Other Components,” above) and one or more types ofbase (sodium hydroxide, potassium hydroxide, ammonia, triethyl amine,sodium bicarbonate, etc.)

As noted above, the desired fluorescent agent may include both the redfluorescent agent, the yellow fluorescent agent as well as one or moretypes of the fluorescent brighteners. The desired resin may include morethan one type of resin. It is desirable for FRET pairs to be formed inthe same fluorescent latex in order to facilitate FRET. However, as alsonoted above, separate fluorescent latexes may be prepared and used,e.g., one fluorescent latex comprising the yellow fluorescent agent andanother fluorescent latex comprising the red fluorescent agent.

The resulting fluorescent agent/resin/solvent mixture is heated to atemperature (e.g., from 30° C. to 80° C., 40° C. to 75° C., 45° C. to70° C.) and for a time (e.g., 20 minutes to 5 hours, 30 minutes to 2hours, 1 hour) while mixing to homogenize the mixture. Additional basemay be added to neutralize the resin while mixing. Mixing is carried outto ensure homogenization and to provide fluorescent agent-incorporatedresin particles having a desired size. (Mixing and homogenization isfurther described below with respect to toners.) An amount ofsurfactant, and/or a biocide may be added. Finally, organic solvents maybe removed by distillation. Water may be added during this process tokeep the desired solid content. The resulting fluorescent orange latexmay be used to form any kind of composition in which fluorescence isdesired. Illustrative compositions include toners and inkjet printingcompositions, thereby rendering such compositions fluorescent. Theseillustrative compositions are further described below.

The fluorescence of the fluorescent orange latexes as well as theexistence of FRET occurring in the fluorescent orange latexes may beconfirmed and quantified using a spectrodensitometer (such as Hunter,X-Rite, etc.) or a fluorescence spectrometer, operated in accordancewith the manufacturer's instructions. These systems may be used todetermine lightness L*, color channels, a* and b*, and reflectance forthe fluorescent orange latexes. Regarding lightness L*, the CIELAB colorspace (also known as CIE L*a*b* or sometimes abbreviated as simply “Lab”color space) is a color space defined by the International Commission onIllumination (CIE). It expresses color as three values: L* for thelightness from black (0) to white (100), a* from green (−) to red (+),and b* from blue (−) to yellow (+).

Because three parameters are measured, the space itself is athree-dimensional real number space, which allows for infinitely manypossible colors. In practice, the space is usually mapped onto athree-dimensional integer space for digital representation, and thus theL*, a*, and b* values are usually absolute, with a pre-defined range.The lightness value, L*, represents the darkest black at L*=0, and thebrightest white at L*=100. The color channels, a* and b*, represent trueneutral gray values at a*=0 and b*=0. The a* axis represents thegreen-red component, with green in the negative direction and red in thepositive direction. The b* axis represents the blue-yellow component,with blue in the negative direction and yellow in the positivedirection. The scaling and limits of the a* and b* axes will depend onthe specific implementation, but they often run in the range of ±100 or−128 to +127 (signed 8-bit integer).

As noted above, the present fluorescent orange latexes are characterizedby a color channel a* of from 40 to 85 and a color channel b* of from 40to 85. The fluorescent orange latexes having at least one FRET pair ofSolvent Red 49 and Solvent Yellow 98 and exhibiting FRET (due toappropriate concentration and homogeneous distribution) arecharacterized as having significantly higher lightness L* andreflectance values as compared to a comparative fluorescent latex havinga different combination of red and yellow fluorescent agents (e.g.,Solvent Red 49 and Solvent Yellow 160:1). Lightness L* and reflectanceis even greater by incorporating a fluorescent brightener.

Toners

In order to form the present toners, any of the resins described abovemay be provided as an emulsion(s), e.g., by using a solvent-based phaseinversion emulsification process. The emulsions may then be utilized asthe raw materials to form the toners, e.g., by using an emulsionaggregation and coalescence (EA) process. However, the toners may beprepared using other processes. As noted above, any of the fluorescentorange latexes described above may be used in the toner preparationprocess to form fluorescent orange toners.

The toner may also include a wax, which may be incorporated into thetoner as a separate dispersion of the wax in water. However, the tonergenerally does not include any pigments or any other colorants besidesthe fluorescent agents described above.

Wax

Optionally, a wax may be included in the present toners. A single typeof wax or a mixture of two or more different waxes may be used. A singlewax may be added, for example, to improve particular toner properties,such as toner particle shape, presence and amount of wax on the tonerparticle surface, charging and/or fusing characteristics, gloss,stripping, offset properties, and the like. Alternatively, a combinationof waxes can be added to provide multiple properties to the tonercomposition.

When included, the wax may be present in an amount of, for example, fromabout 1 weight % to about 25 weight % by weight of the toner or fromabout 5 weight % to about 20 weight % by weight of the toner particles.

When a wax is used, the wax may include any of the various waxesconventionally used in emulsion aggregation toners. Waxes that may beselected include waxes having, for example, an average molecular weightof from about 500 to about 20,000 or from about 1,000 to about 10,000.Waxes that may be used include, for example, polyolefins such aspolyethylene including linear polyethylene waxes and branchedpolyethylene waxes, polypropylene including linear polypropylene waxesand branched polypropylene waxes, polymethylene waxes,polyethylene/amide, polyethylenetetrafluoroethylene,polyethylenetetrafluoroethylene/amide, and polybutene waxes such ascommercially available from Allied Chemical and Petrolite Corporation,for example POLYWAX™ polyethylene waxes such as commercially availablefrom Baker Petrolite, wax emulsions available from Michaelman, Inc. andthe Daniels Products Company, EPOLENE N15™ commercially available fromEastman Chemical Products, Inc., and VISCOL 550P™, a low weight averagemolecular weight polypropylene available from Sanyo Kasei K. K.;plant-based waxes, such as carnauba wax, rice wax, candelilla wax,sumacs wax, and jojoba oil; animal-based waxes, such as beeswax;mineral-based waxes and petroleum-based waxes, such as montan wax,ozokerite, ceresin, paraffin wax, microcrystalline wax such as waxesderived from distillation of crude oil, silicone waxes, mercapto waxes,polyester waxes, urethane waxes; modified polyolefin waxes (such as acarboxylic acid-terminated polyethylene wax or a carboxylicacid-terminated polypropylene wax); Fischer-Tropsch wax; ester waxesobtained from higher fatty acid and higher alcohol, such as stearylstearate and behenyl behenate; ester waxes obtained from higher fattyacid and monovalent or multivalent lower alcohol, such as butylstearate, propyl oleate, glyceride monostearate, glyceride distearate,and pentaerythritol tetra behenate; ester waxes obtained from higherfatty acid and multivalent alcohol multimers, such as diethylene glycolmonostearate, dipropylene glycol distearate, diglyceryl distearate, andtriglyceryl tetrastearate; sorbitan higher fatty acid ester waxes, suchas sorbitan monostearate, and cholesterol higher fatty acid ester waxes,such as cholesteryl stearate. Examples of functionalized waxes that maybe used include, for example, amines, amides, for example AQUA SUPERSLIP6550™, SUPERSLIP 6530™ available from Micro Powder Inc., fluorinatedwaxes, for example POLYFLUO 190™, POLYFLUO 200™, POLYSILK 19™, POLYSILK14™ available from Micro Powder Inc., mixed fluorinated, amide waxes,such as aliphatic polar amide functionalized waxes; aliphatic waxesconsisting of esters of hydroxylated unsaturated fatty acids, forexample MICROSPERSION 19™ also available from Micro Powder Inc., imides,esters, quaternary amines, carboxylic acids or acrylic polymer emulsion,for example JONCRYL 74™, 89™, 130™, 537™, and 538™, all available fromSC Johnson Wax, and chlorinated polypropylenes and polyethylenesavailable from Allied Chemical and Petrolite Corporation and SC Johnsonwax. Mixtures and combinations of the foregoing waxes may also be usedin embodiments. Waxes may be included as, for example, fuser rollrelease agents. In embodiments, the waxes may be crystalline ornon-crystalline.

In embodiments, the toner is prepared by an EA process, such as byaggregating a mixture of an emulsion comprising a resin; the redfluorescent agent, the yellow fluorescent agent, and if present, thefluorescent brightener (provided as one or more fluorescent latexes, butpreferably one to ensure FRET); and optionally, a wax (provided as aseparate dispersion); and then coalescing the mixture. The emulsioncomprising the resin may comprise one or more resins or different resinsmay be provided as different emulsions. The emulsion(s) comprising theresin generally do not comprise and thus, are free of the fluorescentagents. In order to ensure a homogeneous distribution of the FRET pairas well as to achieve FRET without fluorescence quenching in the finaltoner, in the EA process, the red-yellow FRET pair is provided as theone or more fluorescent latexes (and preferably, one) separate from theother components of the mixture and as opposed to simply adding thefluorescent agents themselves to the mixture.

Next, the mixture may be homogenized which may be accomplished by mixingat about 600 to about 6,000 revolutions per minute. Homogenization maybe accomplished by any suitable means, including, for example, an IKAULTRA TURRAX T50 probe homogenizer. An aggregating agent may be added tothe mixture. Any suitable aggregating agent may be utilized. Suitableaggregating agents include, for example, aqueous solutions of a divalentcation or a multivalent cation material. The aggregating agent may be,for example, an inorganic cationic aggregating agent such as apolyaluminum halide such as polyaluminum chloride (PAC), or thecorresponding bromide, fluoride, or iodide; a polyaluminum silicate suchas polyaluminum sulfosilicate (PASS); or a water soluble metal saltincluding aluminum chloride, aluminum nitrite, aluminum sulfate,potassium aluminum sulfate, calcium acetate, calcium chloride, calciumnitrite, calcium oxylate, calcium sulfate, magnesium acetate, magnesiumnitrate, magnesium sulfate, zinc acetate, zinc nitrate, zinc sulfate,zinc chloride, zinc bromide, magnesium bromide, copper chloride, andcopper sulfate; or combinations thereof. The aggregating agent may beadded to the mixture at a temperature that is below the glass transitiontemperature (T_(g)) of the resin (s). The aggregating agent may be addedto the mixture under homogenization.

The aggregating agent may be added to the mixture in an amount of, forexample, from about 0 weight % to about 10 weight % by weight of thetotal amount of resin, from about 0.2 weight % to about 8 weight % byweight of the total amount of resin, or from about 0.5 weight % to about5 weight % by weight of the total amount of resin.

The particles of the mixture may be permitted to aggregate until apredetermined desired particle size is obtained. A predetermined desiredsize refers to the desired particle size to be obtained as determinedprior to formation, and the particle size being monitored during thegrowth process until such particle size is reached. Samples may be takenduring the growth process and analyzed, for example with a CoulterCounter, for volume average particle size. The aggregation thus mayproceed by maintaining an elevated temperature, or slowly raising thetemperature to, for example, in embodiments, from about 30° C. to about100° C., in embodiments from about 30° C. to about 80° C., or inembodiments from about 30° C. to about 50° C. The temperature may beheld for a period time of from about 0.5 hours to about 6 hours, or inembodiments from about hour 1 to about 5 hours, while stirring, toprovide the aggregated particles. Once the predetermined desiredparticle size is reached, a shell may be added (although a shell is notrequired). The volume average particle size of the particles prior toapplication of a shell may be, for example, from about 3 μm to about 10μm, in embodiments, from about 4 μm to about 9 μm, or from about 6 μm toabout 8 μm.

Shell Resin

After aggregation, but prior to coalescence, a resin coating may beapplied to the aggregated particles to form a shell thereover. Any ofthe resins described above may be utilized in the shell. In embodiments,an amorphous polyester resin is utilized in the shell. In embodiments,two amorphous polyester resins (of different types) are utilized in theshell. In embodiments, a crystalline polyester resin and two differenttypes of amorphous polyester resins are utilized in the core and the twodifferent types of amorphous polyester resins are utilized in the shell.The shell resins generally do not comprise, and thus, are free of, thefluorescent agents.

The shell may be applied to the aggregated particles by using the shellresins in the form of emulsion(s) as described above. Such emulsions maybe combined with the aggregated particles under conditions sufficient toform a coating over the aggregated particles. For example, the formationof the shell over the aggregated particles may occur while heating to atemperature of from about 30° C. to about 80° C. or from about 35° C. toabout 70° C. The formation of the shell may take place for a period oftime from about 5 minutes to about 10 hours or from about 10 minutes toabout 5 hours.

Once the desired size of the toner particles is achieved, the pH of themixture may be adjusted with a pH control agent, e.g., a base, to avalue of from about 3 to about 10, or in embodiments from about 5 toabout 9. The adjustment of the pH may be utilized to freeze, that is tostop, toner growth. The base utilized to stop toner growth may includeany suitable base such as, for example, alkali metal hydroxides such as,for example, sodium hydroxide, potassium hydroxide, ammonium hydroxide,combinations thereof, and the like. In embodiments, a chelating agentsuch as ethylene diamine tetraacetic acid (EDTA) may be added to helpadjust the pH to the desired values noted above. Other chelating agentsmay be used.

In embodiments, the size of the core-shell toner particles (prior tocoalescence) may be from about 3 μm to about 10 μm, from about 4 μm toabout 10 μm, or from about 6 μm to about 9 μm.

Coalescence

Following aggregation to the desired particle size and application ofthe shell (if any), the particles may then be coalesced to the desiredfinal shape, the coalescence being achieved by, for example, heating themixture to a temperature of from about 45° C. to about 150° C., fromabout 55° C. to about 99° C., or about 60° C. to about 90° C., which maybe at or above the glass transition temperature of the resins utilizedto form the toner particles. Heating may continue or the pH of themixture may be adjusted (e.g., reduced) over a period of time to reachthe desired circularity. The period of time may be from about 1 hours toabout 5 hours or from about 2 hours to about 4 hours. Various buffersmay be used during coalescence. The total time period for coalescencemay be from about 1 to about 9 hours, from about 1 to about 8 hours, orfrom about 1 to about 5 hours. Stirring may be utilized duringcoalescence, for example, from about 20 rpm to about 1000 rpm or fromabout 30 rpm to about 800 rpm.

After aggregation and/or coalescence, the mixture may be cooled to roomtemperature. The cooling may be rapid or slow, as desired. A suitablecooling process may include introducing cold water to a jacket aroundthe reactor. After cooling, the toner particles may be screened with asieve of a desired size, filtered, washed with water, and then dried.Drying may be accomplished by any suitable process for drying including,for example, freeze-drying.

In the toner, the total amount of the fluorescent agents (red, yellow,and fluorescent brightener, if present) may be present in an amount of,for example, from 0.1 weight % to 10 weight % by weight of the toner.This includes a total amount of from 0.1 weight % to 8 weight % byweight of the toner, from 0.2 weight % to 6 weight % by weight of thetoner, from 0.5 weight % to 5 weight % by weight of the toner, and from1 weight % to 2 weight % by weight of the toner. These ranges are usefulto ensure an appropriate concentration so as to achieve FRET while alsopreventing fluorescence quenching. The relative amounts of the red andyellow fluorescent agents and of the fluorescent brightener to the totalamount of red and yellow fluorescent agents may be those as describedabove with respect to the fluorescent orange latex.

In the toner, a crystalline resin may be present, for example, in anamount of from about 1 weight % to about 85 weight % by weight of thetoner, from about 5 weight % to about 50 weight % by weight of thetoner, or from about 10 weight % to about 35 weight % by weight of thetoner. An amorphous resin or combination of amorphous resins may bepresent, for example, in an amount of from about 5 weight % to about 95weight % by weight of the toner, from about 30 weight % to about 90weight % by weight of the toner, or from about 35 weight % to about 85weight % by weight of the toner. In embodiments, crystalline andamorphous resins are used and the weight ratio of the resins is fromabout 80 weight % to about 60 weight % of the amorphous resin and fromabout 20 weight % to about 40 weight % of the crystalline resin. In suchembodiments, the amorphous resin may be a combination of different typesof amorphous resins, e.g., a combination of two different types ofamorphous resins. In embodiments, one of the amorphous resins has anM_(n) or M_(w) that is greater than the other.

Other Additives

In embodiments, the toners may also contain other optional additives.For example, the toners may include positive or negative charge controlagents. Surface additives may also be used. Examples of surfaceadditives include metal oxides such as titanium oxide, silicon oxide,aluminum oxides, cerium oxides, tin oxide, mixtures thereof, and thelike; colloidal and amorphous silicas, such as AEROSIL®, metal salts andmetal salts of fatty acids such as zinc stearate, calcium stearate, andmagnesium stearate, mixtures thereof and the like; long chain alcoholssuch as UNILIN 700; and mixtures thereof. Each of these surfaceadditives may be present in an amount of from about 0.1 weight % toabout 5 weight % by weight of the toner or from about 0.25 weight % byweight to about 3 weight % by weight of the toner.

Developers and Carriers

The toners may be formulated into a developer composition. Developercompositions can be prepared by mixing the toners with known carrierparticles, including coated carriers, such as steel, ferrites, and thelike. Such carriers include those disclosed in U.S. Pat. Nos. 4,937,166and 4,935,326, the entire disclosures of each of which are incorporatedherein by reference. The toners may be present in the carrier in amountsof from about 1 weight % to about 15 weight % by weight, from about 2weight % to about 8 weight % by weight, or from about 4 weight % toabout 6 weight % by weight. The carrier particles can also include acore with a polymer coating thereover, such as polymethylmethacrylate(PMMA), having dispersed therein a conductive component like conductivecarbon black. Carrier coatings include silicone resins such as methylsilsesquioxanes, fluoropolymers such as polyvinylidiene fluoride,mixtures of resins not in close proximity in the triboelectric seriessuch as polyvinylidiene fluoride and acrylics, thermosetting resins suchas acrylics, mixtures thereof and other known components.

Applications

The toners may be used in a variety of xerographic processes and with avariety of xerographic printers. A xerographic imaging process includes,for example, preparing an image with a xerographic printer comprising acharging component, an imaging component, a photoconductive component, adeveloping component, a transfer component, and a fusing component. Inembodiments, the development component may include a developer preparedby mixing a carrier with any of the toners described herein. Thexerographic printer may be a high-speed printer, a black and whitehigh-speed printer, a color printer, and the like. Once the image isformed with the toners/developers, the image may then be transferred toan image receiving medium such as paper and the like. Fuser roll membersmay be used to fuse the toner to the image-receiving medium by usingheat and pressure.

Inkjet Printing Compositions

Another illustrative composition that may be formed from the presentfluorescent orange latexes is an inkjet printing composition. Suchcompositions are configured to be jettable via an inkjet printingsystem. Such compositions may include any of the disclosed fluorescentorange latexes, a solvent (such as water), optionally, a co-solvent(such as a water soluble or water miscible organic solvent), andoptionally, an additive such as a surfactant, a viscosity modifier toadjust the viscosity of the inkjet printing composition, or a surfaceleveling agent to adjust the surface tension of the inkjet printingcomposition. The desired components may be combined and mixed in thedesired amounts. The inkjet printing compositions may be used withcommercially available inkjet printing systems. Illustrative solvents,co-solvents, additives, illustrative amounts, and illustrative inkjetprinting systems include those as described in U.S. Pat. Pub. No.20190367753 which is hereby incorporated by reference in its entirety.In using such inkjet printing compositions to form an image, the inkjetprinting composition may be deposited on a desired substrate via aninkjet printing system. The solvent(s) may then be evaporated from theas-deposited inkjet printing composition.

EXAMPLE

The following Example is being submitted to illustrate variousembodiments of the present disclosure. The Example is intended to beillustrative only and is not intended to limit the scope of the presentdisclosure. Also, parts and percentages are by weight unless otherwiseindicated. As used throughout this patent specification, “roomtemperature” refers to a temperature of from 20° C. to 25° C.

Fluorescent latexes were prepared as follows. A mixture of 120 g of afirst type of an amorphous polyester resin, 80 g of a second type of anamorphous polyester resin, one or more fluorescent agents (see Table 1below) were dissolved in a mixture of acetone, ethyl acetate and aqueousammonia solution with a ratio of (145/48/40 g) in a 2L reactor at 40° C.Additional base solution was added to each mixture to completelyneutralize the polyester resins. After about one hour and completehomogenization, deionized water was added to each mixture. The organicsolvents were removed by applying a vacuum and water was added duringthis process to maintain the amount of desired water (to achieve adesired solids %). Finally, the resulting emulsion was filtered througha 25 μm sieve. Emulsions had an average particle size of about 250 nm,and a solids content of about 30%. The total fluorescent agent contentin the emulsion was about 1%. A surfactant (Calfax) and a biocide(Proxel GXL) were added to stabilize the fluorescent latex and preventbiogrowth.

TABLE 1 Fluorescent Latexes. Fluorescent Solvent Red Solvent YellowSolvent Yellow Brightener Sample 49 (pph) 160:1 (pph) 98 (pph) (pph) 10.4 — 4.0 2.0 2 0.4 — 4.0 — 3 0.6 — 1.8 1.8 4 0.4 — 2.5 1.0 5 0.4 1.8 —— 6 0.6 1.8 — 1.8 7 — — 2.0 2.0 8 2.0 — — — 9 1.8 — — 1.8

Fluorescent toners were made using the fluorescent latexes of Table 1 aswell as combinations of the fluorescent latexes of Table 1. An emulsionaggregation process was used as described herein.

Specifically, for each toner, a mixture was formed by combining thefollowing: one or more of the fluorescent latexes of Table 1; a firstemulsion comprising a crystalline polyester resin; a second emulsioncomprising the first type of amorphous polyester resin; and the thirdemulsion comprising the second type of amorphous polyester resin. Next,the mixture was acidified. Next, aluminum sulfate (ALS) solution wasadded slowly while homogenizing the mixture after its pH was adjusted tobelow 5. The highly viscous mixture was transferred to a 2L reactor andaggregation initiated by increasing the temperature to about 45° C. Whenthe particle size (D50v) reached about 7.0 μm, an emulsion containingthe two amorphous polyester resins was added to the mixture to form ashell over the particles and the particles were allowed to continuegrow. The particles were frozen by adding a chelating agent (EDTA) and abase (NaOH). The reactor temperature was increased to about 84° C. forcoalescence. The heating was stopped when the particles reached thedesired circularity. The particle slurry was quenched, the particleswere then sieved, and filtered under vacuum. The filtered particles werewashed with deionized water and freeze-dried.

Color analysis was conducted for the fluorescent orange toners printedon papers using Gretag X-rite type instrument. The results are shown inFIG. 1 for some of the toners. Specifically, the axes of FIG. 1correspond to the color channel a* range and color channel b* rangecovering the orange color space and the a*, b* values obtained forseveral fluorescent orange toners are labeled. The results show that thefluorescent orange latexes comprising Solvent Yellow 98 and Solvent Red49 (Samples 1-4) provide fluorescent orange toners that cover a muchlarger area in the orange color space, i.e., provide a much greatergamut of orange color as compared to fluorescent orange latexescomprising Solvent Yellow 160:1 and Solvent Red 49 (Samples 5-6).

Reflectance spectra were collected for the fluorescent toners printed onpapers using Gretag X-rite type instrument. The results are shown inFIG. 2 for some of the toners. Toner 1 was formed from a mixture whichincluded the fluorescent latex of sample 1. Toner 2 was formed from amixture which included the fluorescent latex of sample 2. Toner 3 wasformed from a mixture which included the fluorescent latex of sample 3.Toner 4 was formed from a mixture which included the fluorescent latexof sample 4. The results confirm the emission of orange fluorescencefrom the toners. These results also show that the fluorescent orangetoners comprising Solvent Yellow 98 and Solvent Red 49 cover a largearea in the orange color space (the peak reflectance shifts from about600 nm to 610 nm). In addition, the results show that the peakreflectance (i.e., value of the reflectance at the peak) may beincreased by using greater amounts of Solvent Yellow 98 as compared toSolvent Red 49 (compare Toner 1 having a SY98:SR49 ratio of 10, to Toner4 having a SY98:SR49 ratio of 6.25 to Toner 3 having a SY98:SR49 ratioof 3). Finally, the results show the peak reflectance may be furtherincreased by including a fluorescence brightener (compare Toner 1 and 2having the same SY98:SR49 ratio of 10, but Toner 1 have a fluorescencebrightener and Toner 2 without the fluorescence brightener). Theincreased peak reflectance is believed to be due to additional FREToccurring between the fluorescence brightener and Solvent Yellow 98.

It will be appreciated that variants of the above-disclosed and otherfeatures and functions or alternatives thereof, may be combined intomany other different systems or applications. Various presentlyunforeseen or unanticipated alternatives, modifications, variations orimprovements therein may be subsequently made by those skilled in theart, which are also intended to be encompassed by the following claims.

What is claimed is:
 1. A fluorescent orange latex comprising water andfluorescent agent-incorporated resin particles, the particles comprisinga resin, Solvent Red 49 as a red fluorescent agent, Solvent Yellow 98 asa yellow fluorescent agent, and a fluorescent brightener having afluorescence emission spectrum that overlaps with an absorption spectrumof the yellow fluorescent agent, wherein the fluorescent orange latexhas a weight ratio of the Solvent Yellow 98 to the Solvent Red 49 in arange of from 20:1 to 0.5:1, and wherein the fluorescent orange latexexhibits Förster Resonance Energy Transfer (FRET) under illuminationwith light having a wavelength to excite the yellow fluorescent agentand FRET under illumination with ultraviolet light.
 2. The fluorescentorange latex of claim 1, wherein the fluorescence emission spectrum ofthe fluorescent brightener and the absorption spectrum of the yellowfluorescent agent have a degree of overlap of from 30% to 100%.
 3. Thefluorescent orange latex of claim 1, wherein the fluorescent brighteneris Fluorescent Brightener
 184. 4. The fluorescent orange latex of claim1, having a total amount of the red fluorescent agent, the yellowfluorescent agent, and the fluorescent brightener in a range of from 0.5weight % to 5 weight % by weight of the fluorescent orange latex and aweight ratio of the fluorescent brightener to the red and yellowfluorescent agents in a range of from 1:10 to 1:0.5.
 5. The fluorescentorange latex of claim 1, wherein the particles have an average size in arange of from 20 nm to 1000 nm.
 6. The fluorescent orange latex of claim1, wherein the fluorescent orange latex exhibits a peak reflectance ofat least 155% under illumination with ultraviolet light.
 7. Thefluorescent orange latex of claim 1, wherein the resin is a combinationof two different types of resins.
 8. The fluorescent orange latex ofclaim 7, wherein the two different types of resins are present in aweight ratio of from 2:3 to 3:2.
 9. The fluorescent orange latex ofclaim 7, wherein the two different types of resins are two amorphouspolyester resins.
 10. The fluorescent orange latex of claim 9, whereinthe two amorphous polyester resins are a poly(propoxylatedbisphenol-co-terephthlate-fumarate-dodecenylsuccinate) and apoly(propoxylated-ethoxylatedbisphenol-co-terephthalate-dodecenylsuccinate-trimellitic anhydride).11. The fluorescent orange latex of claim 1, having a total amount ofthe red fluorescent agent, the yellow fluorescent agent, and thefluorescent brightener in a range of from 0.5 weight % to 5 weight % byweight of the fluorescent orange latex and a weight ratio of thefluorescent brightener to the red and yellow fluorescent agents in arange of from 1:10 to 1:0.5, and wherein the resin is a combination oftwo different types of amorphous resins present in a weight ratio offrom 2:3 to 3:2.
 12. The fluorescent orange latex of claim 11, whereinthe fluorescent brightener is Fluorescent Brightener 184 and wherein thetwo different types of amorphous polyester resins are apoly(propoxylated bisphenol-co-terephthlate-fumarate-dodecenylsuccinate)and a poly(propoxylated-ethoxylatedbisphenol-co-terephthalate-dodecenylsuccinate-trimellitic anhydride).13. The fluorescent orange latex of claim 12, wherein the particles havean average size in a range of from 20 nm to 1000 nm.
 14. The fluorescentorange latex of claim 13, wherein the fluorescent orange latex exhibitsa peak reflectance of at least 155% under illumination with ultravioletlight.